1. Field of the Invention
The present invention relates to a head lifting device for moving a magnetic or optical head toward and away from a data-recording disk such as a magnetic disk, optical disk, MO (magneto-optical) disk. It also relates to a disk apparatus incorporating such a head lifting device.
2. Description of the Related Art
Conventional head lifting devices are disclosed in JP-A-6(1994)-20326, U.S. Pat. No. 5,500,838, JP-B2-8(1996)-31264 and JP-B2-8(1996)-10499 for example. Among these, the first three documents disclose similar head lifting mechanisms, in which a head-supporting arm is caused to pivot about a predetermined axis. The last document discloses a different type of mechanism from those disclosed in the first three documents.
Specifically, FIG. 23 of the accompanying drawings shows the principal components of a magneto-optical disk apparatus disclosed in JP-A-6(1994)-20326. As seen from the figure, the conventional disk apparatus includes a magnetic head 90 and a head-supporting arm 91. The magnetic head 90 is attached to the free end of the arm 91. The opposite end or base end of the arm 91 is formed with a through-hole 92 into which a horizontal pin 93 is inserted. Thus, as shown in the figure, the arm 91 is vertically pivotable about the pin 93, thereby moving the head 90 toward or away from the MO disk D. When the magnetic head 90 is held the uppermost position, the MO disk D is easily loaded into or unloaded from the disk apparatus. To perform data-writing or data-reading with the MO disk D, the arm 91 is caused to pivot to the lowermost position, so that the head 90 is held adjacent to the disk D.
FIGS. 24A and 24B show the principal components of a magneto-optical disk apparatus disclosed in JP-B2-8(1996)-10499. As shown in FIG. 24A, the conventional disk apparatus includes a horizontally movable frame 94 and an elastic head-supporting arm 95 attached to the upper part of the frame 94. The downwardly diagonal arm 95 carries a magnetic head 90 at its lower end, to position the head 90 adjacent to the MO disk D. The conventional disk apparatus is also provided with a stationary pin 96 protruding horizontally under the upper part of the frame 94. The position of the pin 96 is adjusted so that it comes into contact with the arm 95 when the frame 94 is moved in the Na-direction shown in FIG. 24B. Thus, as the frame 94 is moved in the Na-direction, the elastic arm 95 will bump into the pin 96 and consequently be flattened, as shown in the figure. As a result of this, the magnetic head 90, attached to the lower end of the arm 95, will be brought away from the MO disk D.
The above-described conventional disk apparatuses have been found disadvantageous in the following points.
In the first type of conventional apparatus shown in FIG. 23, it is necessary to provide some play between the pin 93 and the through-hole 92 for allowing smooth pivotal movement of the arm 91. Due to this play, however, the positioning of the head 90 relative to the recording surface of the disk D tends to become inaccurate. To address this problem, the conventional apparatus is provided with an upright positioning pin 98 to engage with an elongated opening 97 formed in the arm 97. Here again, some play needs to be provided between the pin 98 and the opening 97, whereby the problem of inaccurate positioning of the head 90 will remain unsolved.
In the second type of conventional apparatus shown in FIGS. 24A and 24B, the above-described inaccurate positioning of the head will not be a problem. Disadvantageously, however, the head-supporting arm 95 may lose its initial elasticity after it has been repeatedly deformed through contact with the pin 96. Since this problem is apt to be exacerbated as the arm 95 is bent to a greater extent, the movable range of the magnetic head 90 cannot be made large enough to facilitate the loading and unloading of the Disk D.
The present invention has been proposed under the above-described circumstances, and its object is to provide a simple structure which allows a read/write head to move a great distance (or stroke) relative to a data storage disk without compromising the accuracy of head positioning procedure.
According to a first aspect of the present invention, there is provided a head lifting device includes: a head-supporting member including a first end and a second end opposite to the first end; a head element supported by the first end of the head-supporting member; a base member for supporting the second end of the head-supporting member; and connecting means for pivotably connecting the base member to the second end of the head-supporting member. The connecting means includes at least one hole and at least one protrusion held in sliding engagement with the hole. The protrusion as a whole is prevented from passing through the hole.
With such an arrangement, no play will be provided between the protrusion and the hole. Thus, it is possible to accurately perform the positioning of the head element (carried by the head-supporting member) relative to e.g. a data storage disk. When such accurate positioning is possible, a magnetic head (an example of the claimed head element) can be made appropriately small, since there is no need to generate an unduly strong magnetic field to compensate for the otherwise inaccurate head positioning operation. Further, in such an instance, the coil inductance of the magnetic head can be made smaller, which is advantageous to improving the data transfer speed.
The head element may be an optical head other than a magnetic head.
According to a preferred embodiment of the present invention, the hole may be formed in the head-supporting member, while the protrusion may be formed on the base member. Alternatively, the hole may be formed in the base member, while the protrusion may be formed on the head-supporting member.
Preferably, the protrusion may include a spherical portion engaging with the hole. In this manner, the head-supporting member can pivot smoothly on the protrusion.
Preferably, the hole may have a circular or triangular configuration.
According to another preferred embodiment of the present invention, the protrusion may include anon-spherical portion. For instance, the protrusion may be a prism or pyramid. Here, the xe2x80x9cpyramidxe2x80x9d is defined as a solid or hollow shape with a square or triangular base and sloping sides that meet in a point at the top. Of course, the protrusion may have other configurations.
According to another preferred embodiment of the present invention, the connecting means may include first and second protrusions spaced from each other in a direction perpendicular to a line connecting the first and the second ends of the head-supporting member. The first and the second protrusions may be engaged with a single hole of the connecting means.
According to still another preferred embodiment of the present invention, the connecting means may be provided with first and second holes engaging with the first and the second protrusions, respectively.
According to still another preferred embodiment of the present invention, the hole and the protrusion may be elongated in a direction perpendicular to a line connecting the first and the second ends of the head-supporting member.
The protrusion may be formed separately from the head-supporting member and the base member. Alternatively, the protrusion may be formed integral with either one of the head-supporting member and the base member.
The protrusion may be made up of a solid metal ball used in e.g. a ball bearing. Instead of having a completely round figure, the protrusion may include a flat surface to be adhered to either one of the head-supporting member and the base member.
Preferably, the base member may be provided with a stopper to abut against a particular portion of the head-supporting member for facilitating the positioning of the head element.
Preferably, the head lifting device of the present invention may further comprise urging means to urge the head-supporting member toward the base member for keeping the hole in pressing contact with the protrusion.
Specifically, the urging means may be provided with first and second spring pieces pressing against first and second portions of the head-supporting member, respectively. The first and the second portions may preferably be spaced from each other in a direction connecting the first and the second ends of the head-supporting member.
Preferably, the head lifting device of the present invention may further comprise a movable lifting plate formed with an elongated opening. Accordingly, the head-supporting member may be provided with a post held in sliding engagement with the elongated opening. The post may be provided with an enlarged head portion, so that it is prevented from accidentally coming off the elongated opening.
According to a second aspect of the present invention, there is provided a disk apparatus including: a spindle on which a data storage disk is mounted; a head element brought into facing relation to the disk; a head-supporting member for supporting the head element; a base member for supporting the head-supporting member; and connecting means for pivotably connecting the base member to the head-supporting member. The connecting means may include at least one hole and at least one protrusion held in sliding engagement with the hole, wherein the protrusion as a whole is prevented from passing through the hole.
Preferably, the disk apparatus of the present invention may further include a lifting plate provided with a presser member to press the disk onto the spindle.
Other features and advantages of the present invention will become apparent from the detailed description given below with reference to the accompanying drawings.